Fuselage: Chem-Mill Skin Panels

1 FAA Aviation Safety SPECIAL AIRWORTHINESS INFORMATION BULLETIN SUBJ: Fuselage: Chem-Mill Skin Panels SAIB: NM-17-06 Date: January 4, 2017 This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin (SAIB) advises owners and operators of certain The Boeing Company Model 737-200, -200C, -300, -400, and -500 series airplanes of a new inspection procedure for cracking in the fuselage skin panels at the chem-mill steps.

Background

Airworthiness Directive (AD) 2011-24-12 and AD 2012-26-02, require inspections for cracking at the chem-mill steps of the fuselage skin in several locations on the Boeing Model 737 series airplanes listed above. The inspections use the Ultrasonic Phased Array methodology specified in the Boeing Non Destructive Testing (NDT) Manual Part 4, Section 53-30-07, dated July 1, 2016. This NDT methodology provides an adequate level of safety for compliance with those ADs.

To provide human factors improvements when inspecting large areas of the fuselage skin panels, Boeing published a new inspection procedure in the Boeing 737 NDT Manual, Part 4, Section 53-30-12, dated November 1, 2016, in conjunction with its corresponding probe.

The FAA recently approved Boeing Alternative Method of Compliance (AMOC) Notices: 737-53A1234 AMOC 02, dated September 22, 2016, and 737-53A1301 AMOC 01, dated September 22, 2016, allowing the use of the procedure in the Boeing 737 NDT Manual, Part 4, Section 53-30- 12, dated November 1, 2016, as an acceptable alternative to NDT Manual Part 4, Section 53-30-07, required by AD 2011-24-12 and AD 2012-26-02.

Recommendations

The FAA recommends that operators of the affected airplanes follow the inspection procedure outlined in Boeing 737 NDT Manual, Part 4, Section 53-30-12, dated November 1, 2016.

For Further Information Contact

Jennifer Tsakoumakis, Aerospace Engineer, Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 562-627- 5264; fax: 562-627-5210; email: [email protected].

For Related Service Information Contact

Boeing Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740; telephone 562-797-1717; Internet https://www.myboeingfleet.com.